About the authors

Reto Meier has been helping Android developers create the best applications possible for their users since the initial Android release in 2007. Reto is an experienced software developer with more than 20 years of experience in application design and development. He has spent 10 years as a Developer Advocate, contributing countless articles, online training, conference talks, and YouTube videos to the developer community.

Ian Lake has approached Android development from multiple angles over the course of the last 8 years. Ian has worked professionally on high profile Android apps as an application developer, provided outreach to the development community as a Developer Advocate, and has contributed to improving the Android framework APIs themselves as part of the Android Framework team.

INTRODUCTION xxxi

CHAPTER 1: HELLO, ANDROID 1

Android Application Development 1

A Little Background 2

The Not-So-Distant Past 3

Living in the Future 3

The Android Ecosystem 3

Pre-installed Android Applications 4

Android SDK Features 5

What Does Android Run On? 6

Why Develop for Mobile? 6

Why Develop for Android? 7

Introducing the Development Framework 7

What Comes in the Box 8

Understanding the Android Software Stack 8

The Android Run Time 10

Android Application Architecture 11

Android Libraries 12

CHAPTER 2: GETTING STARTED 13

Getting Started Developing Android Apps 14

Developing for Android 15

What You Need to Begin 15

Creating Your First Android Application 20

Getting Started Writing Android Apps Using Kotlin 35

Using the Android Support Library Package 36

Developing for Mobile and Embedded Devices 39

Hardware-Imposed Design Considerations 39

Considering the User's Environment 43

Developing for Android 44

Android Development Tools 48

Android Studio 49

The Android Virtual Device Manager 51

The Android Emulator 51

Android Profiler 52

The Android Debug Bridge 54

APK Analyzer 54

The Lint Tool 55

Monkey, Monkey Runner, and Espresso UI Testing 55

Gradle 56

CHAPTER 3: APPLICATIONS AND ACTIVITIES AND FRAGMENTS, OH MY! 57

Applications, Activities, and Fragments 58

The Components of an Android Application 58

The Android Application Life Cycle, Priority, and Process States 59

Introducing the Android Application Class 61

A Closer Look at Android Activities 61

Creating Activities 62

Using the AppCompatActivity 63

The Activity Life Cycle 64

Responding to Memory Pressure 71

Introducing Fragments 73

Creating New Fragments 73

The Fragment Life Cycle 74

Introducing the Fragment Manager 79

Adding Fragments to Activities 79

Communicating Between Fragments and Activities 85

Fragments without User Interfaces 86

Building an Earthquake Viewer Application 87

CHAPTER 4: DEFINING THE ANDROID MANIFEST AND GRADLE BUILD FILES, AND EXTERNALIZING RESOURCES 95

The Manifest, Build Files, and Resources 96

Introducing the Android Manifest 96

Configuring the Gradle Build 101

Gradle Settings File 101

Project Gradle Build File 102

Module Gradle Build Files 102

Externalizing Resources 107

Creating Resources 108

Using Resources 119

Creating Resources for Different Languages and Hardware 122

Runtime Configuration Changes 126

CHAPTER 5: BUILDING USER INTERFACES 129

Fundamental Android Design 130

Density-Independent Design 130

Android User Interface Fundamentals 131

Assigning User Interfaces to Activities 132

Introducing Layouts 132

Defining Layouts 134

Using Layouts to Create Device-Independent User Interfaces 136

Optimizing Layouts 139

The Android Widget Toolbox 143

Working with Lists and Grids 144

Recycler View and Layout Managers 145

Introducing Adapters 146

Returning to the Earthquake Viewer Application 149

Introducing Data Binding 150

Enabling Data Binding 151

Variables in Data Binding 152

Data Binding for the Earthquake Viewer Application 153

Creating New Views 155

Modifying Existing Views 155

Creating Compound Controls 159

Creating Simple Compound Controls as a Layout 161

Creating Custom Views 162

Using Custom Controls 176

CHAPTER 6: INTENTS AND BROADCAST RECEIVERS 177

Using Intents and Broadcast Receivers 178

Using Intents to Launch Activities 178

Explicitly Starting New Activities 179

Implicit Intents and Late Runtime Binding 179

Determining If an Intent Will Resolve 180

Returning Results from Activities 181

Using Platform-Native Actions to Launch Activities 184

Creating Intent Filters to Receive Implicit Intents 186

Defining an Intent Filter 186

Using Intent Filters for Plug-Ins and Extensibility 194

Introducing Linkify 198

Native Linkify Link Types 198

Creating Custom Link Strings 199

Using the Match Filter 200

Using the Transform Filter 200

Using Intents to Broadcast Events 200

Broadcasting Events with Intents 201

Listening for Intent Broadcasts with Broadcast Receivers 202

Registering Broadcast Receivers in Code 203

Registering Broadcast Receivers in Your Application Manifest 204

Managing Manifest Receivers at Run Time 204

Monitoring Device State Changes through Broadcast Intents 205

Introducing the Local Broadcast Manager 207

Introducing Pending Intents 208

CHAPTER 7: USING INTERNET RESOURCES 211

Connecting to the Internet 211

Connecting, Downloading, and Parsing Internet Resources 212

Why Build a Native Internet App? 212

Connecting to an Internet Resource 213

Performing Network Operations on Background Threads Using View Models, Live Data, and Asynchronous Tasks 214

Parsing XML Using the XML Pull Parser 219

Connecting the Earthquake Viewer to the Internet 220

Parsing JSON Using the JSON Parser 228

Using the Download Manager 233

Downloading Files 233

Customizing Download Manager Notifications 235

Specifying a Download Location 237

Canceling and Removing Downloads 238

Querying the Download Manager 238

Best Practices for Downloading Data without Draining the Battery 241

An Introduction to Internet Services and Cloud Computing 242

CHAPTER 8: FILES, SAVING STATE, AND USER PREFERENCES 245

Saving Files, States, and Preferences 246

Saving and Restoring Activity and Fragment Instance

State Using the Lifecycle Handlers 246

Retaining Instance State with Headless Fragments and View Models 248

View Models and Live Data 248

Headless Fragments 251

Creating and Saving Shared Preferences 252

Retrieving Shared Preferences 253

Introducing On Shared Preference Change Listeners 254

Configuring Auto Backup of Application Files and Shared Preferences 254

Building a Preference UI 256

Using the Preference Support Library 256

Defining a Preference Screen Layout in XML 257

Introducing the Preference Fragment 260

Creating a Settings Activity for the Earthquake Monitor 261

Including Static Files as Resources 267

Working with the Filesystem 267

File-Management Tools 267

Creating Files on Application-Specifi c Internal Storage 268

Creating Files on Application-Specifi c External Storage 268

Accessing Public Directories Using Scoped Directory Access 270

Sharing Files Using File Provider 274

Creating a File Provider 274

Sharing a File Using a File Provider 275

Receiving a File from a File Provider 275

Accessing Files from Other Applications Using the Storage Access Framework 275

Requesting Temporary Access to Files 276

Requesting Persistent Access to Files 277

Requesting Access to Directories 277

Creating New Files 278

Using URI-Based Permissions 278

CHAPTER 9: CREATING AND USING DATABASES 281

Introducing Structured Data Storage in Android 282

Storing Data Using the Room Persistence Library 282

Adding the Room Persistence Library 283

Defining a Room Database 284

Persisting Complex Objects Using Type Convertors 286

Defining Room Database Interactions Using Data Access Objects 288

Performing Room Database Interactions 291

Monitoring Query Result Changes with Live Data 292

Persisting Earthquakes to a Database with Room 294

Working with SQLite Databases 298

Input Validation and SQL Injection 299

Cursors and Content Values 299

Defining a Database Contract 300

Introducing the SQLiteOpenHelper 300

Opening Databases with the SQLite Open Helper 302

Opening and Creating Databases without the SQLite Open Helper 303

Adding, Updating, and Deleting Rows 303

Querying a Database 305

Extracting Values from a Cursor 307

Introducing the Firebase Realtime Database 308

Adding Firebase to Your App 309

Defining a Firebase Database and Defining Access Rules 311

Adding, Modifying, Deleting, and Querying Data from a Firebase Realtime Database 313

CHAPTER 10: CONTENT PROVIDERS AND SEARCH 317

Introducing Content Providers 318

Why Should I Use Content Providers? 318

Creating Content Providers 319

Creating the Content Provider's Database 320

Registering Content Providers 321

Publishing Your Content Provider's URI Address 321

Implementing Content Provider Queries 322

Content Provider Transactions 325

Sharing Files Using a Content Provider 327

Adding Permission Requirements to Content Providers 328

Accessing Content Providers with Content Resolvers 330

Querying Content Providers 330

Cancelling Queries 333

Querying for Content Asynchronously with a Cursor Loader 333

Adding, Deleting, and Updating Content 336

Accessing Files Stored in Content Providers 338

Accessing Permission-Restricted Content Providers 339

Using Native Android Content Providers 341

Accessing the Call Log 341

Using the Media Store Content Provider 342

Using the Contacts Content Provider 344